It has long been a goal of ophthalmic surgeons to provide patients with alternatives to eyeglasses. Witness the development of the contact lens, radial keratotomy and lasik or laser vision correction surgery. It is estimated that in the year 2000, over two million Lasik procedures will be performed. Notwithstanding the popularity of laser surgery, it is not without its drawbacks and deficiencies. For example, recent data has shown that approximately 5-10% of the patients undergoing laser refractive surgery will have sub-optimal results such as, a final vision correction which still requires some sort of optical correction or the patient will experience cataract-like “halos”. In addition, it has been estimated that up to 50% of the patients post laser surgery experience dry eye symptoms on an ongoing basis.
In response to the foregoing, ophthalmic surgeons have turned to intraocular implant surgery in an effort to advance the art of refractive vision correction. For example, U.S. Pat. No. 5,192,319 to Worst discloses an intraocular refractive lens which is surgically positioned in the anterior chamber and is used in addition to the natural lens to correct for myopic and hyperopic refraction error. The lens comprises an optical portion (the optic) having an inner concave and an outer convex shape. Attached to the outer periphery of the optic is one or more pairs of flexible pincer arms which are adapted to pinch a small portion of the anterior surface of the iris to maintain the implant in place. Notwithstanding the foregoing, the Worst lens has not been widely adopted. This is because the lens requires a hard, non-flexible material to fixate to the iris, thus requiring a large 6 mm or more incision. Also, the amount of tissue contact of greater than 7 square mm with the implant and the iris have caused clinical issues of endothelial cell loss of greater than two percent (2%) per year, whereas normal cell loss is one percent (1%) per year. In addition, the Worst lens is difficult to implant and requires a two handed ambidextrous surgical technique to insert and attach to the iris, skills, which are found in relatively few ophthalmologists.
Other anterior chamber implants have also been attempted without success. For example, U.S. Pat. No. 4,575,374 to Anis discloses an anterior chamber lens comprising an optic and four haptics, each of which flexes independently of the others. U.S. Pat. No. 4,166,293 also to Anis discloses an anterior chamber implant for cataract replacement having an optic and three loops that extend downward and are adapted to fit behind the iris. A fourth loop overlies on of the other loops and overlies the iris when the implant is in place within the eye. The implant is held in place by an attachment member, which connects the fourth loop with the underlying loop by penetrating through the iris. Another anterior chamber implantable lens is disclosed in U.S. Pat. No. 4,177,526 to Kuppinger wherein a pair of opposing arms are attached to the optic. The respective arms are inserted behind the iris and pinch the rear of the iris to hold the implant in place. Another anterior chamber implant lens is disclosed in U.S. Pat. No. 5,047,052 to Dubroff, which teaches an optic, and four haptics extend outwardly therefrom. The haptics are flexible and independently movable. Further, once the implant is inserted and positioned by conventional means, the ends of the haptics are adapted to rest within the optical angle, i.e., the intersection of the cornea and the iris. It is notable that none of the foregoing implant lenses have been widely adopted and in fact only one of the lens (i.e., Worst Lens) is currently in limited use in the European market, as they all experienced surgical or clinical failures including, lens insertion and attachment problems, intraocular or iris bleeding, inflammation, endothelial cell loss, tissue deformation, or lens induced glaucoma.
Accordingly, it is an object of the present invention to provide an improved refractive implant, which solves the aforementioned problems.
A further object of the present invention is to provide an improved refractive implant, which is minimally surgically invasive and maintains the natural anatomical processes (e.g., fluid flow, endothelial cell loss, etc.) of the eye.
Another object of the present invention is to provide an improved refractive implant having reduced side effects, for example dry eyes and inflammation.
An additional object of the present invention is to provide an improved refractive implant, which is easily implantable and removable, if necessary.
A still further object of the present invention is to provide an improved refractive implant, which accurately corrects vision, thus obviating the need for subsequent surgeries.
A correlated object of the present invention is to provide an improved refractive implant, which is easy to manufacture.
Yet another object of the present invention is to provide an improved refractive implant, which does not require expensive equipment, such as lasers.